JavaScript hash map implementation

hashMap.js

var JSL = JSL || {};
JSL.HashMap = function () {
    "use strict";
    var keys = [],
        values = [];
    function indexOf(key) {
        var i = 0;
        if (keys.indexOf !== undefined) {
            return keys.indexOf(key);
        }
        for (i = 0; i < keys.length; i += 1) {
            if (key === keys[i]) {
                return i;
            }
        }
        return -1;
    }
    function searchFor(value) {
        var i = 0;
        if (values.indexOf !== undefined) {
            return values.indexOf(value);
        }
        for (i = 0; i < values.length; i += 1) {
            if (value === values[i]) {
                return i;
            }
        }
        return -1;
    }
    function put(key, value) {
        var index = indexOf(key);
        if (index === -1) {
            keys.push(key);
            values.push(value);
            index = indexOf(key);
        } else {
            values[index] = value;
        }
        return index;
    }
    function get(key) {
        if (typeof key === "number") {
            return {
                key: keys[key],
                value: values[key]
            };
        }
        var index = indexOf(key);
        return values[index];
    }
    function remove(key) {
        var index = indexOf(key);
        if (index > -1) {
            keys.splice(index, 1);
            values.splice(index, 1);
            return true;
        }
        return false;
    }
    return {
        get: get,
        remove: remove,
        put: put,
        indexOf: indexOf,
        searchFor: searchFor
    };
};